合金工模具钢Fe-M-C淬火马氏体回火的二次硬化研究进展

含W、Mo、V等合金元素的工模具钢Fe M C淬火马氏体在 5 0 0～ 6 0 0℃回火因纳米级简单间隙相M2 C和MC碳化物脱溶析出 ,提高回火马氏体的硬度而出现淬火马氏体回火的二次硬化。当前对淬火马氏体回火二次硬化的研究趋向是利用现代研究方法进一步分析和研究合金马氏体的脱溶贯序 ,全面得出弥散沉淀物的组成和淬火合金马氏体二次硬化的主体机制 ,开发出充分利用二次硬化的新型高性能工模具钢。

中频感应炉冶炼合金工模具钢的成分控制和合金元素烧损探析

以科研，生产中的工模具钢为对象，其中以５％Ｃｒ型热作模具钢４Ｃｒ５ＭｏＳｉＶ１（即Ｈ１３）的批生产数据为重点，通过统计分析得出：中频感应炉冶炼合金工模具钢有诸多优点，化学成分控制准确可靠，合金元素烧损少，除Ｓｉ以外，其它元素收得率均高于９５％，主要技术经济指标良好。

稀土合金化对高碳高合金工模具钢的影响

莱氏体共晶碳化物粗大不均是严重影响高碳高合金工模具钢使役性能的不利因素。除了改变凝固冷却条件调控莱氏体共晶碳化物以外,国内外在利用稀土合金化手段改善共晶碳化物的形貌与分布方面也进行了大量研究,来提高高碳高合金工模具钢的热加工性能与韧性。本文简要介绍了高碳高合金工模具钢的生产工艺现状,阐述了高碳高合金工模具钢稀土合金化的研究进展,对比总结了稀土合金化研究现状中稀土元素的添加技术与添加量。另外,重点梳理了稀土合金化对高碳高合金工模具钢组织与性能的影响。最后,展望了稀土高碳高合金工模具钢的工业化生产与应用。

铝合金挤压工模具技术的发展概况与趋势

简略地论述了工模具在铝合金挤压生产中的重要作用与特殊地位;介绍了铝挤压工模具技术的主要内容;着重分析了国内外挤压工模具设计制造水平及创新亮点。

铝合金厚板的性能、应用及市场

介绍了热轧铝合金厚板的成分与性能,着重阐述了铸造铝合金厚板的性能、生产、市场与应用。国外一些铝业公司研发出了一批具有优异性能的铸造厚板用铝合金,如美国铝业公司的 Mic-6合金、柯鲁斯铝业公司的 Giantal、Hokotol 合金,在国民经济的各个部门特别是工模具制造业(含铝锭铸造结晶器)与航空器制造业获得了日益广泛的应用。用铸造铝合金厚板制造塑料模具,与钢模具相比其成本至少低35%;用铝合金厚板制造的航空器与机器零件可取代大多数锻件。铝合金厚板是高附加值产品,生产铸造铝合金厚板是一项高技术,中国应建设铸造铝合金厚板项目。

电化教育在金工课教学中的作用

作为金工课教学中必备的教学手段——电化教育正在起着越来越明显的作用。据不完全统计,目前各兄弟院校分散制作的金工电教录像片约2000多分钟,配合金工教材的幻灯片有三套,等等。这些教学手段的应用对促进金工教学水平的提高,对培养学生分析问题、解决问题的能力,对开拓同学思路,开扩眼界,扩大知识面起到了积极的作用。尤其自1984年4月以来,在教育部金工教材编审小组的直接领导下,制定了1984—1990年金工电化教学工作规划。通过细致的调研,确定了1984—1986年金工电视片制作计划。通过现有电教教学片的交流、协商约稿,落实了制作单位。 1984年10月于成都对焊接片进行了审稿,并制订了1985年工作计划。从此。

华泽铝电铸造厂改进精炼工艺质量升成本降

山西华泽铝电有限公司铸造厂合金工区对精炼工艺进行技术革新,采用不锈钢管代替镀锌管进行精炼作业,统计数据显示,不锈钢材质的精炼管使用寿命是原镀锌管的10倍以上,不仅大大降低了生产成本,而且提高了产品质量。据悉,精炼过程中精炼管要与铝液进行接触,以前合金工区使用的镀锌管,材质为普通钢铁,熔点低,与铝液接触十几分钟就会出现管口熔化，使得铝液铁含量升高，造成铝液污染。

国内外铝挤压工模具技术的发展概况与创新亮点

论述了工模具在铝合金挤压生产中的重要作用与特殊地位;介绍了铝挤压工模具技术的主要内容;着重分析了国内外挤压工模具设计制造水平及创新亮点、铝挤压工模具的使用、修理、氮化技术及现代化管理。

Constructing processing map of Ti40 alloy using artificial neural network

Based on the experimental data of Ti40 alloy obtained from Gleeble-1500 thermal simulator,an artificial neural network model of high temperature flow stress as a function of strain,strain rate and temperature was established.In the network model,the input parameters of the model are strain,logarithm strain rate and temperature while flow stress is the output parameter.Multilayer perceptron（MLP） architecture with back-propagation algorithm is utilized.The present study achieves a good performance of the artificial neural network（ANN） model,and the predicted results are in agreement with experimental values.A processing map of Ti40 alloy is obtained with the flow stress predicted by the trained neural network model.The processing map developed by ANN model can efficiently track dynamic recrystallization and flow localization regions of Ti40 alloy during deforming.Subsequently,the safe and instable domains of hot working of Ti40 alloy are identified and validated through microstructural investigations.

Rate controlling mechanisms in hot deformation of 7A55 aluminum alloy

The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization （DRX） existed on the processing maps and lying in 410-450 ＆#176;C and 0.05-1 s-1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization （DRX） domain and the stability regions except dynamic recrystallization （DRX） domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.

Improvement and application of neural network models in development of wrought magnesium alloys

Neural network models of mechanical properties prediction for wrought magnesium alloys were improved by using more reasonable parameters, and were used to develop new types of magnesium alloys. The parameters were confirmed by comparing prediction errors and correlation coefficients of models, which have been built with all the parameters used commonly with training of all permutations and combinations. The application was focused on Mg-Zn-Mn and Mg-Zn-Y-Zr alloys. The prediction of mechanical properties of Mg-Zn-Mn alloys and the effects of mole ratios of Y to Zn on the strengths in Mg-Zn-Y-Zr alloys were investigated by using the improved models. The predicted results are good agreement with the experimental values. A high strength extruded Mg-Zn-Zr-Y alloy was also developed by the models. The applications of the models indicate that the improved models can be used to develop new types of wrought magnesium alloys.

Hot deformation behavior of extruded AZ80 magnesium alloy

The hot deformation behavior of extruded AZ80 magnesium alloy was studied through hot compression tests performed at temperatures ranging from 250 to 450 ~C with strain rates varying from 0.001 to 10 s-1. The flow stress was corrected due to the deformation heating. The Zener-Hollomon parameter （Z parameter） and processing map were established to describe the hot deformation behavior. The results indicate that the applicable deformation should be conducted at the strain rate of 0.1 s-~ and the temperature range of 350-400 ~C. Besides, the relationship between the microstructure evolution and Z parameter was also discussed. High temperature and low strain rate result in a low Z parameter, which leads to full dynamic recrystallization （DRX） and large DRX grain size in the microstructure. Considering processing map and microstructure, the hot deformation should be carried out at the temperature of 400 ~C and the strain rate of 0.1 s 1.

DRY GRINDING OF Ti6Al4V ALLOY WITH FLAP WHEELS

The grindability of alloy Ti6AI4V with zireonia alumina and silicon carbide flap wheels, and the effect of process parameters on grinding forces, grinding temperature and surface integrity are studied. The grinding forces are measured by KISTLER 9265B dynamometer. The grinding temperature response is obtained by NI USB-621X signal collection system. Ground surface morphology and the metallographic structure are observed by the Hirox KN-7700 stereoscopic microcope and the Quanta200 scanning electron microscope （SEM）. Surface roughnesses are measured by Mahr Perthometer M1 instrument. The surface microhardnesses are detected by HXS-1000 microhardness tester.

Compositional optimization of glass forming alloys based on critical dimension by using artificial neural network

An artificial neural network （ANN） model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on the dc and their de values were predicted by the ANN model. Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were prepared by injecting into copper mold. The amorphous structures and the determination of the dc of as-cast alloys were ascertained using X-ray diffraction. The results show that the predicted de values of glass forming alloys are in agreement with the corresponding experimental values. Thus the developed ANN model is reliable and adequate for designing the composition and predicting the de of glass forming alloy.

Influence of thermomechanical processing on microstructure,texture evolution and mechanical properties of Al-Mg-Si-Cu alloy sheets

Influence of thermomechanical processing on the microstructure, texture evolution and mechanical properties of A1-Mg-Si-Cu alloy sheets was studied systematically. The quite weak mechanical properties anisotropy was obtained in the alloy sheet through thermomechanical processing optimizing. The highly elongated microstmcture is the main structure for the hot or cold-rolled alloy sheets. H {001 } （110） and E { 111 } （110） are the main texture components in the surface layer of hot-rolled sheet, while ]/-fibre is dominant in quarter and center layers. Compared with the hot-rolled sheet, the intensities offl-fibre components are higher after the first cold rolling, but H {001 }（110） component in the surface layer decreases greatly. Almost no deformation texatre can be observed after intermediate annealing. And fl-fibre becomes the main texture again after the final cold rolling. With the reduction of the thickness, the through-thickness texture gradients become much weaker. The through-thickness recrystallization texture in the solution treated sample only has cubeyD {001 }（310） component. The relationship among thermomechanical processing, microstructure, texture and mechanical orouerties was analyzed.

Hot deformation behavior of TC11/Ti-22Al-25Nb dual-alloy in isothermal compression

The high-temperature flow behavior of TCll/Ti-22Al-25 Nb electron beam（EB） weldments was investigated by the isothermal compression tests at the temperature of 900-1060℃ and the strain rate of 0.001-10 s-（-1）.Based on the experimental data,the constitutive equation that describes the flow stress as a function of strain rate and deformation temperature is obtained.The apparent activation energy of deformation is calculated,which decreases with increasing the strain and the value is 334 kJ/mol at strain of 0.90.The efficiency of power dissipation η changes obviously with the variation of deformation conditions.Under the strain rates of 0.01,0.1 and 1 s-（-1）,the value of η increases with increasing the true strain for different deformation temperatures.While the value of η decreases with increasing the strain under the strain rates of 0.001 and 10 s-（-1）.The optimum processing condition is（t（opi）=1060℃,ε（opi）=0.1 s-（-1）） with the peak efficiency of 0.51.Under this deformation,dynamic recrystallization（DRX） is observed obviously in the microstructure of welding zone.Under the condition of 1060℃ and 0.001 s-（-1）,the deformation mechanism is dominated by dynamic recovery（DRV） and the value of η decreases sharply（η=0.02）.The flow instability is predicted to occur since the instability parameter ξ（ε）becomes negative.The hot working process can be carried out safely in the domain with the strain rate of 0.001-0.6 s-（-1） and the temperature of 900-1060℃.

Grain refinement in AZ31 magnesium alloy rod fabricated by extrusion-shearing severe plastic deformation process

A new severe plastic deformation （SPD） method that is extrusion-shearing （ES）, which includes initial forward extrusion and shearing process subsequently, was developed to fabricate the fine grained AZ31 Mg alloys. The components of ES die were manufactured and installed to gleeble1500D thermo-mechanical simulator. Microstructure observations were carried out in different positions of ES formed rods. The results show that homogeneous microstructures with mean grain size of 2 μm are obtained at lower temperature as the accumulated true strain is 2.44. Occurring of continuous dynamic recrystallization （DRX） is the main reason for grain refinement during ES process. The experimental results show that the ES process effectively refines the grains of AZ31 magnesium. The production results of ES extrusion with industrial extruder under different extrusion conditions show that the ES extrusion can be applied in large-scale industry.

Intelligent method to develop constitutive relationship of Ti-6Al-2Zr-1Mo-1V alloy

The isothermal compression tests were carried out in the Thermecmastor-Z thermo-simulator at temperatures of 800, 850, 900, 950, 1000 and 1050 ℃ and the strain rates of 0.01, 0.1, 1 and 10 s-1. The influence of deformation temperature and strain rate on the flow stress of Ti-6Al-2Zr-IMo-IV alloy was studied. Based on the experimental data sets, the high temperature deformation behavior of Ti-6A1-2Zr-IMo-IV alloy was presented using the intelligent method of artificial neural network （ANN）. The results indicate that the predicted flow stress values by ANN model is quite consistent with the experimental results, which implies that the artificial neural network is an effective tool for studying the hot deformation behavior of the present alloy. In addition, the development of graphical user interface is implemented using Visual Basic programming language.

Application of cyclic upsetting-extrusion to semi-solid processing of AZ91D magnesium alloy

The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.

Superplasticity of AZ31 magnesium alloy prepared by friction stir processing

Microstructure and tensile behaviors of AZ31 magnesium alloy prepared by friction stir processing（FSP） were investigated.The results show that microstructure of the AZ31 hot-rolled plate with an average grain size of 92.0 μm is refined to 11.4 μm after FSP.The FSP AZ31 alloy exhibits excellent plasticity at elevated temperature,with an elongation to failure of 1050% at 723 K and a strain rate of 5×10-4 s-1.The elongation of the FSP material is 268% at 723 K and 1×10-2 s-1,indicating that high strain rate superplasticity could be achieved.On the other hand,the hot-rolled base material,which has a coarse grain structure,possesses no superplasticity under the experimental conditions.